Lurasidone is a well known dopaminergic (D2) and serotonin (5-HT2A) receptor antagonist and is disclosed in U.S. Pat. Nos. 5,780,632 and 5,532,372. Chemically, it is N-[4-[4-(1,2-benzisothiazol-3-yl)-1-piperazinyl]-(2R,3R)-2,3-tetramethyle-ne-butyl]-(1′R,2′S,3′R,4′S)-2,3-bicyclo[2,2,1]heptanedicarboxylmide hydrochloride having the structural formula:

A free form of lurasidone and an acid addition salt thereof are known to have psychotropic activities and are effective as therapeutic agents, particularly for schizophrenia or senile dementia, etc. Senile dementia is broadly classified into Alzheimer's dementia and cerebrovascular dementia, and it can be said that the two make up about 80% of senile dementia.
U.S. Pat. No. 7,727,553 discloses a pharmaceutical preparation in the form of a rapidly disintegrating oral preparation comprising granules comprising lurasidone, two disintegrating agents, a water-soluble excipient and a polymer binder.
U.S. Patent Publication No. US 2009/0285805 discloses a solution-type preparation of lurasidone or acid addition salt thereof prepared by incorporating one or more substances selected from benzyl alcohol, N,N-dimethylacetamide, lactic acid, anhydrous ethanol and propylene glycol.
U.S. Patent Publication No. US 2009/0143404 discloses composition comprises lurasidone, a pregelatinized starch, a water-soluble excipient and water-soluble polymer binder.
In order to secure the bioequivalence when a pharmaceutical preparation having different amounts is administered at the same dose, there was issued “Guideline for Bioequivalence testing of Oral Solid Dosage Forms with Different Content” (Notification No. 64 of the Evaluation and Licensing Division, PMSD dated Feb. 14, 2000), by which it has been required that a pharmaceutical preparation having different amounts should be equivalent in dissolution profile in test solutions such as buffers of pH 1.2, 3.0 to 5.0 and 6.8 (which correspond to the pH values of the stomach, the intestine and the oral cavity, respectively), water, and saline solution, etc.
For medicaments showing a good solubility in water, it is easy to prepare such preparations having equivalent in vitro (dissolution) profile even in different amounts due to their water solubility. On the contrary, for medicaments containing as an active ingredient a slightly water-soluble compound, such as lurasidone (has a solubility of less than several μg/ml in water), it is difficult to prepare a pharmaceutical preparation having equivalent dissolution profile, and even more challenging to have such equivalent in vitro (dissolution) profile over a wide range of medicament content.
The prior art references emphasize on using water-soluble excipients, for example—water-soluble polymer binders, disintegrating agents and there is no disclosure or teaching/suggestion in the art about how to develop stable formulations of lurasidone without employing water-soluble excipients which can also exhibit rapid or modified disintegration as well as equivalent in vitro (dissolution) profile over wide dose range.
Hence there still remains a need for alternative pharmaceutical formulations comprising lurasidone in order to achieve equivalent dissolution profile of the formulations containing wide dose of active ingredient.